Means for controlling the fuel-air ratio of internal-combustion engines



Dec. 14, 1954 A. MURAS ZEW MEANS FOR CONTROLLING THE FUEL-AIR RATIO OF INTERNAL-COMBUSTION ENGINES Filed Feb. 12, 1951 In 0 62127201 -M.Mmwz 6w United States Patent ()fifice 2,696,809 Patented Dec. 14, 1954 MEANS FUR CONTROLLING THE FUEL-AIR RATIO OF INTERNAL-COMBUSTION EN- GINES Alexander Muraszew, London, England, assiguor to C. A. V. Limited, London, England Application February 12, 1951, Serial No. 210,491

2 Claims. (Cl. 123-140) This invention has for its object to provide improved means for controlling the fuel-air ratio in an internal combustion engine, of the kind to which petrol or other liquid fuel is supplied by a variable-delivery injection pump, and the air is supplied through a throttle-controlled manifold.

The invention comprises the combination of means responsive to a difference of gas pressures for actuating the throttle, one of which is the air pressure at the engine side of the throttle, a valve for controlling the said means, a manually operable mechanism adapted to actuate the said valve and also the pump-output controlling means, and means responsive to a difference of gas pressures one of which is the air pressure at the engine side of the throttle for automatically restoring the valve to its previous position after manual actuation of the valve.

In the accompanying drawings:

Figure 1 is a diagram illustrating an embodiment of the invention.

Figure 2 is a fragmentary view illustrating a modification.

Referring to Figure 1, there is provided a chamber a divided into two compartments by a diaphragm b which carries a thrust piece c adapted to act on a lever d for actuating a throttle e of the butterfly-type situated in the air manifold f of the engine, and loaded by a spring (not shown). Passages h, i communicating with the two compartments are controlled by a hollow piston valve j slidable in a cylinder k having a passage in which can be connected by a pipe 11 to the manifold at the engine side of the throttle. This valve j is secured at one end to a diaphragm which divides another chamber p into two compartments. The compartment containing the portion of the valve attached to the diaphragm is open to atmosphere, or is adapted to be connected to the exhaust pipe of the engine. It also contains a spring q which at one end is supported on the diaphragm and at the other end is supported by the adjacent end wall of the compartment. The end of the valve adjacent to the diaphragm is provided with a lateral port r (or ports) through which atmospheric air (or exhaust gas) can. pass along the valve to the remote closed end of the cylinder containing the valve. The other compartment is in communication with the pipe n leading to the manifold at the engine side of the throttle. Also it contains a spring s which at one end is supported by the diaphragm and which at the other end is supported by a thrust piece I which extends through the adjacent end wall of the compartment and at its outer end rests on a manually-operable lever u.

The lever u is connected by a link v or other means to the mechanism which controls the rate of output of the fuel pump w. Also the end of the lever which supports the associated thrust piece 2 is shaped to a cam-like or equivalent form so that a given angular movement of the lever is accompanied by an appropriate axial movement of the thrust piece.

The arrangement is such that the immediate elfect of a movement of the lever u is a variation of the pump output and a movement of the valve j. The latter in turn influences the relative pressures acting on the diaphragm b which actuates the throttle, and results in a corresponding movement of the throttle, the variation of the air flow in the manifold being always preceded by variation of the pump output.

Automatic restriction of the movement of the throttle valve to an extent determined by the amount of movement imparted manually to the lever u is elfeced by the difference of gas pressures acting on the diaphragm 0. Thus for example, if an opening movement is given to the throttle by appropriate displacement of the valve j in response to movement of the lever u, the consequent change of depression of pressure in the manifold will result in a disturbance of the balance of spring and gas pressures acting on the diaphragm 0, and the latter will thereupon return the valve to its previous position and so prevent continued movement of the throttle. Therefore, the throttle is brought to rest at a position corresponding to the movement imparted to the lever u.

II" desired, the valve j may also be actuated by a temperature-responsive device. Thus, as shown in Figure 2, the spring q may be replaced by an elastic capsule x containing air or other gas.

By this invention the fuel-air ratio can be controlled in a manner which obviates a disadvantage of the conventional means of varying this ratio. Hitherto it has been usual to connect the manually operable means to the throttle, and consequently an opening movement of the throttle has been accompanied by a temporary but undesirable weakening of the fuel-air mixture, a condition which persists until corrected by the subsequent increase of the rate of fuel supply. In an apparatus embodying the invention, this condition is reversed, and an increase in the fuel sup ply is accompanied by a temporary but advantageous overrichening of the fuel-air mixture.

The invention is not, however, restricted to the example above described, as the details of construction or arrangement may be varied to suit different requirements. Also in place of the diaphragms mentioned, pistons slidable in cylindrical chambers may be used.

Having thus described my invention What I claim as new and desire to secure by Letters Patent is:

1. In a system for supplying fuel and air to an internal combustion engine, and having an air intake manifold provided with a controlling throttle, and a variable delivery fuel pump provided with output controlling means, means for controlling the fuel-air ratio of the engine, comprising in combination a first fluid-operable means for actuating the throttle in response to a difference between opposing gas pressures, one of which is the air pressure in the air intake manifold at the engine side of the throttle, a valve for controlling the fluid-operable means, a second fluid-operable means for actuating the valve in response to the difference between opposing gas pressures, one of which is the air pressure in the air intake manifold at the engine side of the throttle, manually operable means, a spring through the medium of which the valve is movable in one direction by the manually operable means, but which subsequently permits the valve to be returned to its previous position by the second fluid-operable means Without affecting the position of the manually operable means, and means movable by the manually operable means for actuating the pump output controlling means.

2. A system according to claim 1 and having temperature responsive means acting on the second fluid-operable means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,150,075 Mennesson Mar. 7, 1939 2,189,475 Saur -2 Feb. 6, 1940 2,217,364 Halford et a1 Oct. 8, 1940 2,356,679 Mallory Aug. 22, 1944 2,365,384 Bonnier Dec. 19, 1944 2,426,740 Mock Sept. 2, 1947 2,442,419 Lee, 2d June 1, 1948 

